It is well known that improper automobile tire inflation causes accelerated and uneven tire wear, and increses the risk of tire blow outs which, in turn, presents a traffic safety hazard. Such problems can often be eliminated by monitoring of the tire's pressure and, accordingly, by inflating the tire to the proper pressure.
Many prior methods for measuring automobile tire pressure are known. Such prior devices are generally of three types, namely: (1) a detached pressure gauge which may be temporarily connected to the valve stem of a non-moving tire for purposes of reading tire's pressure; (2) a remote-reading gauge system which has a pressure sensing device which constantly senses tire pressure in communication with a remote indicator (typically in the automobile's dashboard) which allows either constant or intermittant tire pressure monitoring from inside the automobile; and (3) a tire pressure gauge or indicator permanently attached to the tire's valve stem by which the tire pressure can be read directly when the tire is not moving. The present invention is of the latter type of pressure measuring devices.
Prior device which are in permanent communication with a tire's valve stem typically have the indicator component mounted at or near the valve stem and, as such, are typically off-center relative to the tire itself. Because these prior devices are off-center (relative to the tire and the automobile's axle they must be designed to endure high centrifugal forces which may be encountered when the automobile moves. Such high forces can be destructive to the device as well as to the automobile.
Another problem of such prior devices is that, in the event the device becomes detached from the valve stem while the automobile is in motion, the device may become a high velocity projectile and thus present a safety hazard.
Another problem of such prior devices is that, because of the eccentricity of the load that they add to the tire, the automobile's tire may become unbalanced, thus presenting a safety problem and causing an uneven and unsafe ride for the automobile's passengers.
Another problem of such prior devices is that, because of the undesired side-effects relating to a large eccentric load, these devices are typically designed to be very small--often too small for the gauge itself to be read.
For this same reason such pressure indicating devices are typically linear gauges, in which the pressure is read on an extension rod of a displaced pressure sensing piston. Such linear gauges are typically difficult to read. Because alternative indicators, for example, dial gauges and digital gauges, are typically larger and/or heavier than these prior (linear) devices, and because they would effect an even larger eccentric load, prior devices typically do not comprise dial gauges or digital gauges.